be prone to 的to 是作介词还是不定式?例句中有be prone to illness 也有be prone to eat junk food就是说既有be prone to do sth.也有be prone to n.那to到底是作什么?如果说be prone to doing 是正确的吗?

be prone to 的to 是作介词还是不定式?例句中有be prone to illness 也有be prone to eat junk food就是说既有be prone to do sth.也有be prone to n.那to到底是作什么?如果说be prone to doing 是正确的吗? be inclined to 和 be prone to 区别 求关于be...to的词组.如：be devoted to、be sentenced to、(to作介词) be prone to近义词有没有 In favor of 的意思 Thanks. be favorable to 的to是介词吗 be keen to的to是介词吗 be crucial to里面的 to 是介词吗 gmat改错题（ ),all the buildings were reinforced withadditional steel.A:Being prone to earthquakesB:Since the area was known to be prone to earthquakes为什么不选A?all the buildings是主语有什么问题吗？ to 作介词的短语都有哪些呀是to做介词 to什么时候作介词? to什么时候作介词 有什么词组是to作介词 Prone to insipid but unwilling to ordinary. This followed criticism that the rats used in the experiment were prone to cancer anyway.1.used不是应该用被动语态吗,这里有省略什么成份吗,如果有,麻烦详细告知是什么语法点2.be prone to cancer anyway这里的cancer是 to作介词时的用法我知道to作介词时后面跟V的ing形式 可是be used to doing 和is happy to do有什么不同吗？为什么is happy to do不是用doing呢？还有怎么区分到底是动词不定式还是当作介词用时跟V的ing be used to和used to的to是介词还是动词不定式?为什么? 请问英文翻译 skin prone to irritaion to是介词为什么be going to是情态动词